The present invention relates to a steel laminate gasket having main and auxiliary sealing members for sealing around a hole by different surface pressures.
In an internal combustion engine, a gasket is installed between two engine members having a plurality of holes therein, wherein high pressure is formed in cylinder bores, while moderate pressure is formed in water holes. In order to seal around these holes with pressure therein, a gasket is formed to provide high surface pressure around the holes when the gasket is tightened.
In the gasket, however, if large surface pressure is formed around a hole to be sealed, a hole may be deformed by the large surface pressure. Also, in case a cylinder liner is installed in an engine, a large surface pressure is not generally applied onto the cylinder liner. Therefore, high surface pressure is not simply applied around the holes to be sealed.
When high surface pressure can not be applied around a hole, moderate surface pressure is applied around a hole to be sealed, and high surface pressure is further applied outside the portion where moderate surface pressure is applied. The area around the hole is sealed by the combination of the moderate and high surface pressures.
In U.S. Pat. No. 4,739,999, a gasket is provided with several beads, wherein two beads are vertically arranged to provide high surface pressures, and a bead is arranged laterally inside the two bead to provide moderate surface pressure.
In U.S. Pat. No. 4,861,046, two beads are arranged laterally away from each other around a hole to be sealed to provide different surface pressures.
The above prior patents operate as intended. However, when preparing a gasket with a plurality of holes to be sealed with different surface pressures, it is difficult to control surface pressures at portions around the different holes.
On the other hand, a wire ring has been used for sealing around a hole, such as shown in U.S. Pat. No. 4,809,653. The wire ring can be tightened as desired up to high tightening pressure, but since the wire ring can not provide resiliency, the use of the wire ring is limited.
Accordingly, one object of the present invention is to provide a steel laminate gasket having main and auxiliary sealing members, wherein surface pressures applied to the main and auxiliary sealing members can be controlled easily.
Another object of the invention is to provide a steel laminate gasket as stated above, wherein surface pressures around different holes to be sealed can be controlled easily.
A further object of the invention is to provide a steel laminate gasket as stated above, which can be manufactured easily and economically.
Further objects and advantages of the invention will be apparent from the following description of the invention.